The details of the 70th week obviously did not occur at the conclusion of the 69th week in which the Lord was crucified, and therefore is a period following the 69th week by some time, and not sequential.
Dan 9:25 Know therefore and understand, that from the going forth of the commandment to restore and to build Jerusalem unto the Messiah the Prince shall be seven weeks, and threescore and two weeks: the street shall be built again, and the wall, even in troublous times.
To understand the Seventy weeks that were determined upon thy people (Jews) and upon thy holy city (Jerusalem), you need to read it in context. Daniel was praying for his people and the holy city, when the Angel came to explain what would happen. &0 weeks were determined for the people to get things right.
"from the going forth of the commandment to restore and to build Jerusalem unto the Messiah the Prince shall be 69 weeks (seven weeks, and threescore and two weeks).
457BC the decree to restore and build the city. -- 69 weeks (483 years) -- 27AD = Jesus was baptized. The beginning of the public ministry.
(Jesus) "he shall confirm the covenant with many for one week: and in the midst of the week he shall cause the sacrifice and the oblation to cease.
27AD -- 3 1/2 years -- 31AD = Jesus died and the Sacrifice was complete.
They (Jews) still had 3 and a half years to accept Jesus as a nation. But they didn't.
31AD -- 3 1/2 years -- 34AD = they stoned Steven to death when he gave the speech in Acts 7. " Ye stiffnecked and uncircumcised in heart and ears, ...When they heard these things, they were cut to the heart,...And cast him out of the city, and stoned him".
The 70 weeks have come and gone, it was for Gods people and for "...thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy. "